In the past, traditional hand-held implements, such as those commonly used for writing, have generally been provided with a cylindrical shaft which is manipulated by the thumb and index finger of the user acting in conjunction with each other to control the tip of the device so as to accomplish a specified task. Additionally, the users of such traditional cylindrical shaft implements may often utilize the arch as a lever against the working thumb and index finger as a fulcrum, in order to manipulate the implement. Examples of such traditional single tip hand-held implements are writing instruments such as pens and pencils, cutting instruments such as knives and awls, tools such as soldering devices and scribes, painting instruments such as brushes, cosmetics application equipment and digitalizing contacting devices such as computer styluses. During their use, the surface of such traditional implements contacts a relatively small surface area of the user's skin.
Historically, improvements to such traditional hand-held implements concerned the mechanical aspects of the implements, such as new inks, ink flow mechanisms and delivery of the ink to the writing surface. A fundamental disadvantage of traditional implements is that they have only a single rigidly mounted working tip and the ubiquitous cylindrical shaft does not conform well to the surfaces of the user's fingers, palm or closed inner hand.
One of the least developed areas of hand-held implement design is the relationship between the grasping shape of the implement and the natural shape of the user's hand. This has a significant effect on the user's comfort and ability to control and manipulate the implement, particularly when the implement is to be used for a prolonged period of time. Conventional implements contact a relatively small proportion of the surface area of the user's fingers, leaving a large area of the thumb and fingers unused. Further, the bulk of the user's hand is not used to dissipate the physical stress that accompanies the use of the hand-held implement. This situation eventually leads to discomfort for the user over a period of use, as the rigid surfaces of the implement exert pressure (in the form of negative leverage) and friction on the user's fingers. Thus, it is advantageous that a larger percentage of the surface area of the hand and fingers which work with a hand-held implement should contribute to controlling the hand-held implement.
Prior attempts were made to modify hand-held implements to reduce discomfort and fatigue. For example, implements have been produced which have soft rubber coating materials. However, such materials tend to reduce the control of the implement in the hand and easily become soiled. Also, it has been proposed to provide hand-held implements with different concave surfaces. However, these concave surfaces have not overcome the basic problems arising from the basic idea of a cylindrical shaft oriented to extend in a direction between the thumb and index finger of the user and out away from the hand.
Rubin, in U.S. Pat. No. 5,785,443, described a handheld writing instrument with a similar body shape. However, Rubin's design lacks any mechanism for variably extending the implement tip from the main body and retracting the implement tip into the main body. This inability is a major disadvantage, for example, preventing a pen from being stored in a pocket without risking damage to clothing and preventing the inadvertent marking on surfaces other than the target area.